Altered levels of extracellular matrix molecule mRNA in healing rabbit ligaments

RT-PCR methods were used to amplify, semi-quantify, clone and sequence cDNA fragments specific for rabbit extracellular matrix molecules biglycan, collagen I, collagen III, decorin, lumican, versican, fibromodulin, and also glyceraldehyde-3-phosphate dehydrogenase (G3PDH), using RNA isolated from rabbit ligaments. Sequence analysis of two independent clones of PCR products was used to verify the identity of the cDNA. Semi-quantitative RT-PCR was used to study mRNA levels for these matrix molecules in normal and healing rabbit ligament at three, six, and fourteen weeks post-injury. The yield of RNA from the ligament scar was increased at three and six weeks post-injury, but it had returned to near normal levels by fourteen weeks. On a microgram RNA basis, it was demonstrated that biglycan, collagen I, collagen III and lumican mRNA levels are significantly elevated, versican mRNA levels significantly depressed, and decorin and fibromodulin mRNA levels showed no significant change in response to tissue injury in the ligament during the course of healing. These findings suggest that differential regulation of mRNA levels for these extracellular matrix molecules occurs during ligament healing.